1. Field of the Invention
The present invention relates in general to a locking device for doors and, more particularly, to a locking device locked and opened by a magnetic card key, the locking and opening motion of the above locking device being performed by a magnetic interaction between a magnetic force distributed in the card key and a plurality of magnetized pins of the locking device.
2. Description of the Prior Art
As well known to those skilled in the art, various types of locking devices for doors have been proposed. In a conventional locking device for doors, both a lock and inside and outside handle knobs are installed in a door. The above lock includes a locking cylinder with a plurality of spring-biased operating pins. A key slot for receiving a key having specific cuts is axially formed in the center of the locking cylinder. The inside handle knob is provided with a push button for locking the locking device inside the door.
As the above locking device is to be opened by moving the operating pins using a key having specific cuts, the locking device may be somewhat easily picked by any metal object with similar shapes and cuts by someone other than the owner. Therefore, the above locking device does not provide adequate protection from intruders. Therefore, at least one auxiliary lock in addition to the above locking device may be installed in the door in order to achieve improved security. However, such an auxiliary lock would increase the cost. Furthermore, the auxiliary lock cannot achieve the expected security as it too may be picked by any metal object with similar shapes and cuts by someone other than the owner in the same manner as described for the above locking device.
In order to rectify the above problems, a magnetic card key-operated locking device for doors has been proposed. This card key-operated locking device includes both a locking unit and an identifying unit. The identifying unit is for identifying authorized people. In order to open up the door provided with the above locking device, an identifying magnetic card is inserted in the identifying unit. A releasing button of the locking unit may be operated only after the identifying unit identifies the authorized person from the inserted card. That is, the above magnetic card is not used as a key for opening the locking unit but as means for identifying authorized people. In addition, there is another type of magnetic card key-operated locking device wherein a magnetized card is brought into direct contact with a locking unit and thereby opens the locking device by a magnetic interaction between a magnetized contact surface of the card and the locking unit. However, as the locking unit of the above locking device has a simple construction, the locking device may be easily picked by any magnetic material.